Pen



FIG. 1 is a top right side perspective view of a pen in accordance with the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is right side elevation view thereof, the left side elevation view being a mirror image thereof;

FIG. 4 bottom plan view thereof;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a front elevation view thereof.

The broken lines shown in FIGS. 1-4 and 6 illustrate portions of the pen that form no part of the claimed design. 

CLAIM The ornamental design for a pen, as shown and described. 